Objective Bacterial isolation was conducted on tissue samples from diseased pigs in a pig farm in Heyuan City， Guangdong Province， to develop targeted treatment plans and prevention andthe take control measures for the farm.Method Morphological observation， 16S rRNA gene amplification， and sequencing were used for bacterial species identification. Subsequently， serotype typing， virulence gene detection， pathogenicity， and drug sensitivity tests were performed.Result The results showed that the isolated strain appeared as a gray white， semi transparent smooth circle on TSA agar， and formed an α hemolytic ring around the colony on blood agar medium. Staining displayed that the bacterium was a purple Gram positive short chain or long chain streptococcus. The PCR amplification and sequencing analysis of the 16S rRNA gene demonstrated that the isolated strain is Streptococcus suis. Serotype identification revealed that the strain belongs to S. suis type 9， and virulence gene testing indicated that the strain''s virulence genotype is epf+. The pathogenicity test showed that after 6 hours of infection， the mice from the experimental group exhibited different clinical symptoms， with some mice dying. The surviving mice showed some relief of symptoms after 48 hours， indicating that the strain has significant pathogenicity. The results of the drug sensitivity test displayed that the strain shows high sensitivity to ampicillin， ceftriaxone， cefoxitin， and other antibiotics.Conclusion The results of the research in this study could provide scientific basis for the prevention and control of Streptococcus suis.